I like the idea that each lil guy has a different timing when they mine, in practice get that the intended mechanic is to place the kobold on the correct rock for optimal minage. I found it very difficult to do this on the fly though as even without doing anything they mined the rock quite quickly. By the time I found a optimal kobold for a particular rock, it was already almost smashed. I also couldn't figure out what sharpen and train did.
In general I liked it though! with some polish this could be a great (mini)game.